1. High-harmonic generation from noble gases exposed to intense laser fields Gavin Waters Supervisor: Dr. L. J. Frasinski

2. Diagram: Y. Mairesse et al; 'Attosecond Synchronization of High-Harmonic Soft X- rays' Science, Vol 302, 28 November 2003, 1540-1543 Schematic Diagram of Equipment

3. Diagram: P. Agostini, L. F. DiMauro; 'The Physics of Attosecond Light Pulses' Rep. Prog. Phys. 67 (2004) 813-855 Three-step Model of HHG Step 1: Tunnel ionization Step 2: Quasi-classical electron acceleration in strong laser field Step 3: Electron-nucleus recombination, emission of High Harmonic photon Due to this process occurring every half of the optical cycle of the driving beam, only photons of frequency that are odd harmonics of the driving beam are produced

4. Diagram: J. Itatani et al; ' Tomographic Imaging of Molecular Orbitals' Nature, Vol 432, 16 December 2004, 867-871 Electron Wave-packet Model of HHG Electron now represented by its wave-function, ψ Part of the wave-function, ψ g, remains in the ground state Remaining part of wave-function, ψ c, interferes with ψ g on re-collision This interference effect leads to an electron charge oscillation, and the emission of High Harmonic radiation

5. Diagram: J. Tisch, Imperial College Technical Drawing of Apparatus Side view of the HHG equipment. Equipment designed by J. Tisch (Imperial College). The two main components shown are HHG chamber (right) and mirror chamber (left).

6. Diagram: J. Tisch, Imperial College Technical Drawing of Apparatus Top down view of the HHG equipment. Red line represents driving laser beam (pulse duration about 30fs). Green line represents HHG laser beam (pulse duration less than 1fs).

7. HHG equipment used in Saclay experiment

8. Mirror Chamber used in Saclay Experiment

9. ULL, University of Reading